Review: Mycobacterium leprae – millennium resistant! Leprosy control on the threshold of a new era

Authors


correspondence Jan Visschedijk, Royal Tropical Institute, Health Care and Disease Control, Wibautstraat 137J, 1097 DN Amsterdam, The Netherlands. E-mail: j.visschedijk@kit.nlb>

Abstract

Summary Over the past decades, the conditions of leprosy control implementation have changed dramatically. Introduction of multidrug therapy, together with the global effort of the World Health Organization to eliminate leprosy as a public health problem, had a tremendous impact on leprosy control, particularly by decreasing the registered prevalence of the disease. At the beginning of the new millennium, leprosy control programmes face several new challenges. These relate not only to changes in the prevalence of the disease, but also to changes in the context of leprosy control, such as those created by health sector reforms and other disease control programmes. This review discusses current knowledge on the epidemiology of Mycobacterium leprae and some important aspects of leprosy control. It is argued that our understanding is still insufficient and that, so far, no consistent evidence exists that the transmission of leprosy has been substantially reduced. Sustainable leprosy control, rather than elimination, should be our goal for the foreseeable future, which also includes care for patients on treatment and for those released from treatment. This, however, requires new strategies.

Introduction

Throughout history, leprosy has been characterized as a disease responsible for serious deformities and disabilities resulting in stigmatization and psychological and social suffering. Though leprosy has been prevalent in most parts of the world, it vanished in several areas, including northern Europe, long before an efficacious treatment was developed. However, at the end of the 20th century, leprosy was still endemic in many developing countries, particularly affecting the poorest segments of these societies. Every year more than half a million people are diagnosed as leprosy patients, while millions suffer from the sequelae of the disease. Hence in 1991 the World Health Assembly called for a global effort to eliminate leprosy as a public health problem by the end of the second millennium.

Epidemiology

Transmission

Though Mycobacterium leprae was one of the first microorganisms directly associated with a specific disease, large gaps still exist in our knowledge ( WHO 1998a). This applies not only to the pathology and immunology, but also to crucial epidemiological aspects. Figure 1 presents a simplified model of the transmission of M. leprae, indicating that infection does not necessarily lead to any symptom or lesion specific for the disease leprosy. In fact, it is assumed that M. leprae is not very pathogenic and that most infections do not result in symptoms. Early symptoms of leprosy can be self-limiting and skin lesions can heal spontaneously ( Fine 1982).

Figure 1.

Transmission cycle of Mycobacterium Leprae. Modified after Van Beers et al. (1966).

Individuals who suffer from the disease, particularly those with multibacillary (MB) leprosy, are sources for spread of the infection. The most important port of entry and exit of M. leprae is the respiratory system, particularly the nose; its dissemination through skin lesions seems to be less important. But what happens to those who are infected but do not develop the disease? Do some of them become carriers? And if so, are they an important source in the transmission of the M. leprae? There is increasing evidence from nasal polymerase chain reaction (PCR) studies of temporary carriage or even subclinical infection ( Van Beers et al. 1996 ; Cree & Smith 1998) and that infected persons may go through a transient period of nasal excretion, indicating that the mycobacterium is highly infective ( Hatta et al. 1995 ). Patients' household contacts, neighbours, and social contacts have an increased risk of contracting the disease (Van Beers et al. 1999). Whether this is mainly the result of closer contacts to the index case, similar genetic and immunological background, environmental factors, or a combination of all these, has still to be resolved.

A crucial factor in the process from infection to disease is the immune status of the host. Research and debate have focused on whether and how infections with other microorganisms may modify the immune response to M. leprae. It has, for example, been suggested that a previous infection with Mycobacterium tuberculosis may boost the immune system, thereby diminishing the chances of developing leprosy ( Lietman et al. 1997 ). BCG vaccination provides protection against leprosy, although studies have shown the degree of protection to vary from 20% to 80% ( Fine 1995). BCG immunization may also be responsible for a shift in immune response from multibacillary to paucibacillary (PB) leprosy ( Chaudhury et al. 1994 ; Van Beers et al. 1996 ).

The consequences of an infection with the Human Immunodeficiency Virus (HIV) on the risk of developing leprosy remain controversial ( Van Beers et al. 1996 ). Some studies have suggested an association between HIV infection and leprosy ( Borgdorff et al. 1993 ; Van den Broek et al. 1997 ), while others did not find any association ( Pönnighaus et al. 1991 ; Frommel et al. 1994 ; Kawamua et al. 1994 ). Also, it is uncertain whether HIV infection is modifying the expression or course of M. leprae infection ( Sampaio et al. 1995 ). In Ethiopia no evidence was found to support an association between HIV infection and a shift towards multibacillary disease ( Frommel et al. 1994 ), whereas the seroprevalence of HIV was higher in MB patients than in PB patients in Uganda and Tanzania ( Borgdorff et al. 1993 ; Kawuma et al. 1994). These conflicting results may be explained by confounding factors ( Van Beers et al. 1996 ). Globally, however, there is no indication as yet that the HIV epidemic is leading to a significant increase in the number of leprosy patients. The impact of HIV on leprosy may be minimal because it simply takes too much time for an infection of M. leprae to develop symptoms ( Van Beers et al. 1996 ).

Distribution and trends

Table 1 gives an overview of the registered prevalence in 1999 and case detection rate in 1998, as reported by WHO (1999). At the beginning of 1999, more than 800 000 leprosy cases were registered for treatment worldwide. In 1998 a similar number of new cases was detected. The distribution, however, is very uneven. About 75% of the registered patients live in South-east Asia, particularly in India. In 1998, 32 countries had a leprosy prevalence exceeding 1 case per 10 000 population. In absolute terms the global leprosy burden was concentrated in 16 countries ( Table 2), with India as the absolute number one ( WHO 1998b). These national figures, however, conceal clustering within countries and significant differences in prevalence between regions, districts and communities.

Table 1.  Leprosy cases detected and registered (WHO 1999) Thumbnail image of
Table 2.  Cases detected (1998) and registered prevalence (as of 1st January 1998) in 16 leprosy endemic countries (WHO 1988) Thumbnail image of

Figure 2 indicates that the registered prevalence has decreased dramatically over the last decade, but is currently levelling off ( WHO 1998b). Over the same period, however, the case detection rate has been more or less constant for most of the time, although there has been a steady increase since 1995. Though some global trends can be identified, there are significant differences between countries. While in some countries case detection rates are more or less stable (India), in others these rates decrease (China) or even increase (Bangladesh) ( Smith 1997).

Figure 2.

Leprosy trend in 32 endemic countries combined.

Recently, a lively debate has emerged on the significance of these trends (in registered prevalence and case detection rate) for the epidemiology of leprosy in general and the transmission of M. leprae in particular. The use of prevalence, and particularly prevalence of patients registered for treatment ('registered prevalence'), as the main indicator for the epidemiology of leprosy, has several caveats (Box 1).

In principle, incidence is a better measure for monitoring of trends in transmission. However, virtually no information on incidence rates exists ( Fine 1992; Smith 1997). Case detection rates (CDR = all new cases annually registered in health facilities) are substantially flawed in functioning as proxy indicators for incidence rates. Firstly, not all cases detected are in actual fact recent new cases. Some ostensibly new cases may already have suffered from leprosy for several years, but for various reasons (stigma, inaccessibility of health services, opportunity costs) not visited a health facility. They constitute the so-called hidden ‘backlog’ of leprosy cases. Defaulting and re-registering ('shopping'), as well as relapses may also inflate the figures for ‘new’ cases detected. Secondly, detection of new cases depends on the method and intensity of case finding. Active case finding is likely to increase the number of newly detected cases, while a poorly performing programme may identify only a small proportion of all new cases. Active case finding may also overestimate incidence rates, since some new cases are self-healing and should be included neither in prevalence nor in incidence rates. Consequently, the currently available information is inadequate to anticipate trends in leprosy epidemiology and transmission. Worldwide information on the most crucial indicator, incidence, is lacking ( Smith 1997), while trends in CDR may be distorted as a result of confounding and bias ( Meima et al. 1997 ).

Leprosy control

Leprosy control has three main strategic components ( Feenstra 1994): Early detection of patients, their adequate treatment, and providing comprehensive care for the prevention of disabilities and rehabilitation.

Early detection of patients

Patient delay varies with the level of stigma prevailing in a certain area. Although stigma may have been reduced in many countries, it is still considerable in some communities ( Myint et al. 1992 ; Raju & Kopparty 1995; Croft & Croft 1998). Public education and the provision of effective treatment with multidrug therapy (MDT) play an important role in further reducing the stigma linked with the disease ( Jopling 1991). (Multidrug therapy (MDT) was introduced for leprosy control as a response to increasing resistance to monotherapy with dapsone. The regimen for PB patients consists of dapsone and rifampicin for six months, while the regimen for MB patients consists of dapsone, rifampicin and clofazamin for 12 or 24 months. Patients collect a monthly blister pack which contains their daily medication.)

Due to the lack of a single independent ‘gold standard’ for diagnosis, the diagnosis of leprosy is based mainly on clinical symptoms. Laboratory techniques (AFB microscopy) were introduced for a relatively short period of time, but are now being abandoned in several areas where leprosy is still endemic. However, there is a need for an easy-to-use diagnostic test, particularly because leprosy is a relatively rare disease in many countries, with specific knowledge mainly concentrated at central level and much less at the periphery. Recently developed immunological and molecular assays cannot be used as diagnostic tests in routine control programmes, because they do not discriminate clearly between infection, ‘contamination’, and disease ( Van Beers 1998). However, these tests may be useful for the diagnosis of subclinical infections and the detection of sources of transmission.

Adequate treatment

Treatment with MDT of all leprosy patients became the official strategy of the WHO in 1982, when widespread resistance to dapsone had to be confronted. Consequently, research focused particularly on the relapse rate of these new MDT regimens ( Cree & Smith 1998). Different definitions and indicators have been used to describe relapse (rates), which has often hampered comparison between studies. WHO has defined relapse as a patient who successfully completes an adequate course of MDT, but subsequently develops new signs and symptoms of the disease during the surveillance period or thereafter. In general, the number of leprosy relapses reported in control programmes has been low ( Becx-Bleumink 1992; Jesudasan et al. 1996a ; Dasananjali et al. 1997 ; Li et al. 1997 ) and well below the relapse rates reported in, for instance, tuberculosis control programmes.

The 7th WHO Expert Committee on Leprosy considered, based on the results of a multicentre double blind trial ( Grosset 1997; WHO 1997a) with 2–4 years of follow-up, that the 24-month MDT regimen for MB-leprosy can be shortened to 12 months. The Medico-Social Commission of the International Federation of Anti-Leprosy Associations (ILEP) supported the advice of the WHO Expert Committee, because a shortened course would reduce costs for both programme and patient, and would reduce the proportion of defaulters ( ILEP 1998). Fear has been expressed that the relapse rate for those with a relatively high bacterial load may be unacceptably high ( Van Brakel et al. 1989 ; Waters 1998; Lynch 1999). Nevertheless, most leprosy-endemic countries have implemented a shortened 12-month MB-MDT regimen within a year after the Committee met.

A relatively new development is the introduction of a single dose of rifampicin 600 mg plus ofloxacin 400 mg and minocycline 100 mg (ROM) as an acceptable and cost-effective alternative regimen for the treatment of single-lesion PB leprosy. A multicentre double blind trial concluded that ROM is almost as effective as standard 6-month WHO PB-MDT in the treatment of single lesion leprosy ( Single Lesion Multi-Centre Trial Group 1997). However, questions were raised on the methodology of the study ( Lockwood 1997). Furthermore, the debate should be seen in light of the fact that 80% of all single-lesion PB cases are self-healing ( Ekambaram & Sithambaram 1977).

These days, most control programmes report treatment completion rates of 60–90% for PB patients and 40–80% for MB patients ( ILEP 1999). Reasons for nonadherence are reported to be economic (costs of transport, opportunity costs of monthly clinic visits), as well as social and psychological (self-stigma, no improvement of disabilities, mobility). Unfortunately, results from studies are often inconsistent and the exact relationship between these factors and compliance remains largely obscure ( Vadher & Lalljee 1992).

Prevention of disabilities and rehabilitation

Leprosy patients suffering from disabilities, which may develop before, during or after MDT, are often easily recognizable by the characteristic deformities of their eyes, hands and feet. Impairments and disabilities develop in stages, often starting with nerve damage due to neuritis and leprosy reactions and resulting in the loss of protective sensation, as well as the loss of muscle strength and autonomic functions. The International Classification of Impairments, Disabilities and Handicaps gives the following definitions ( WHO 1980):

  • Impairment: any loss or abnormality of psychological, physiological, or anatomical structure or function.

  • Disability: any restriction or lack of ability (resulting from impairment) to perform an activity in the matter of within the range considered normal for a human being.

  • Handicap: A disadvantage resulting from impairment or disability, that limits or prevents the fulfilment of a role that is normal, depending on age, sex, social and cultural factors for the individual.

However, the chain ‘disease-impairment-disability-handicap’ is not a chronological process. Impairment resulting from leprosy always entails at the same time physical, psychological and social consequences and thus involves a disability and a handicap. It ranges from the inability to play a normal role at home and in the community and meeting normal social obligations to complete alienation from society and destitution. Unfortunately, with few exceptions, the link between impairment, disability and handicap has rarely been studied in detail ( Van Brakel 1997). In many concepts describing the burden of disease, including the DALY ( Murray & Lopez 1994), the socio-economic impact of leprosy in terms of handicap is, also for reasons of international comparison, not included.

Since the consequences of leprosy are physical, psychological and socio-economical, rehabilitation covering these aspects should ideally be interrelated and integrated. Physical rehabilitation is a prerequisite for successful socio-economic functioning. Successful coping with impairments and disabilities is an important determinant of motivation for preventing their worsening. In practice, however, physical and socio-economic rehabilitation interventions have often been separated.

Leprosy control programmes tend to consider only physical rehabilitation. In some countries socio-economic rehabilitation is covered by the government through social welfare, NGOs or community-based rehabilitation (CBR) programmes, which address severely deformed and destitute patients living at home or in leprosaria, and may include vocational training, income-generating projects and charity. Most CBR programmes are tailored to specific local needs and consequently differ from country to country and even among different areas of the same country ( Deepak 1995). Integrating all aspects of rehabilitation into CBR programmes remains a major challenge. However, a CBR programme cannot substitute all rehabilitation services, particularly not those relating to identification of at-risk patients and prevention of disabilities ( Deepak 1995), which require close collaboration between community rehabilitation workers and medical staff.

Towards elimination of leprosy by the year 2000

In 1991 the World Health Assembly adopted a resolution to eliminate leprosy as a public health problem by the year 2000 ( WHO 1991). Elimination was defined as a level of prevalence below one case per 10 000. Along with this resolution, WHO advocated an approach consisting of four elements: Making MDT available at community level, Leprosy Elimination Campaigns (LECs), Special Action Projects, and close monitoring of the impact, particularly through assessing the prevalence of leprosy.

The approach has been successful in achieving almost 100% MDT coverage. In many countries LECs have resulted in the detection of a considerable number of cases. Important elements of the campaigns are training of health workers in case finding, educating communities to increase awareness, active case finding and treating patients. In Nepal more than 11 000 new cases were identified during last year's national campaign ( Ministry of Health and Nepal Department of Health Services 1998), while the number of new cases in the previous year was around 7500 ( Ministry of Health Nepal 1998). In 1997 and 1998 LECs were held in 29 Indian States and Union Territories. More than 500 000 health workers were involved and 454 290 new cases were detected ( Directorate General of Health Services 1999).

Though LECs have indeed yielded a substantial number of new cases and may have reduced the backlog of leprosy cases, some questions have been raised about their cost-effectiveness, long-term impact and particularly their diagnostic accuracy. The high number of patients detected during these campaigns may indeed indicate a backlog of patients and an underestimation of the leprosy problem, but also considerable overdiagnosis and thus diagnostic inaccuracy ( WHO 1998c). Another concern is case-holding of patients found through active case finding. Compared to patients who report to health services voluntarily, these patients may be less motivated to complete treatment, and some of them may have limited access to health facilities.

Special Action Projects for the Elimination of Leprosy (SAPEL) are meant to bring MDT to remote areas where routine activities are nonexistant or have proven impractical (no health infrastructure, geographically difficult to access, refugees, etc.). SAPELs have generally been less successful: they resulted in only a limited number of new cases ( WHO 1996; Ebenso 1999), have been relatively expensive and had questionable adherence levels.

While millions of patients have been released from MDT and the global registered prevalence has decreased substantially, it is likely that in several leprosy-endemic countries the elimination target will not be reached. Prevalence rates vary widely within countries and, as a result various regions continue to have relatively high rates.

Nevertheless, the enhanced commitment for the elimination target by the year 2000, to be reached by the main tool for elimination, MDT, has given a strong impetus to leprosy control ( Feenstra 1992). The underlying assumption is that MDT, by making highly infectious patients rapidly noninfectious, will have an impact on the transmission of M. leprae. This assumption, however, has been challenged ( Fine 1992). The degree of its impact, particularly on the incidence of leprosy, is still largely unknown and subject of intensive discussion ( WHO 1998d). Reduced prevalence has mainly resulted from shorter treatment schedules and clearing of registers, not by a decrease in incidence. Nevertheless, WHO is using registered prevalence as the main indicator to monitor progress because of the operational difficulties in measuring incidence.

The postponement of the elimination date to 2005, and the suggestion by WHO that the next five years are necessary to ‘cure the remaining patients’ and that only a ‘limited number of leprosy patients’ may occur after the year 2005 (as stated in the ILEP/WHO draft Strategic Plan 2000–2005 and the Memorandum of Understanding between WHO and Novartis Pharma AG), strengthen the idea that the leprosy problem is on the point of disappearance ( Li et al. 1997 ). Such an approach is likely to be counterproductive, because it may have negative consequences for future support, the funding of research and the implementation of leprosy control activities ( Anonymous 1997). Presently, there is no basis for confidence that the incidence and the number of new leprosy patients detected annually will have been substantially reduced in all currently endemic areas after the year 2005, let alone be zero. Hence, leprosy control activities should not be exclusively directed towards a magic target but towards sustainable leprosy control, far into the new millennium. This requires new strategies, rather than questionable assumptions.

New directions for leprosy control

The introduction of new and relatively short MDT treatment schedules, the expected reduction in priority given to leprosy control, as well as ongoing health sector reforms, make it imperative for national decision-makers to review the policies and strategies for leprosy control. While leprosy-specific field staff was often overburdened 20 years ago, when many patients were on lifelong treatment, they now have to deal with substantially lower patient loads.

However, if the impression is given that the leprosy problem has been ‘eliminated’, political interest will wane, certainly while other diseases such as AIDS, malaria, tuberculosis and noncommunicable diseases require increasing attention. (The use of the term elimination as ‘a public health problem’ is often confused with the definition of elimination as was for instance defined during the Conference on Global Disease Elimination and Eradication as Public Health Strategies, in Atlanta, USA 1998 ( Dowdle & Hopkins 1998). Elimination was here defined as a reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts ( Dowdle 1998). Control was defined as the reduction of disease incidence, morbidity or mortality to a locally acceptable level as result of deliberate efforts; continued measures are required to maintain the reduction.) Though understandable, reduced priority for leprosy should not lead to giving no priority at all. Many examples in the past, e.g. in the case of tuberculosis and malaria, demonstrate that abandoning disease control programmes altogether has serious repercussions when such diseases re-emerge.

The context in which disease control programmes are operating is also changing ( Green & Jochem 1998). Most ministries of health are engaged in reforms, whether slow and incremental or fast and radical. If a disease control programme takes a passive and defensive attitude towards these changes and their possible adverse effects, it might well end up losing an opportunity to influence new health sector policies.

To maintain political commitment is crucial. In this context, promotion of (ex)patient organizations, capable of pressurizing governments to fulfil their responsibilities, could be an important activity. In Brazil, for instance, organizations of patients, ex-patients and committed individuals have gained strength in the past few years. These organizations assist regular health services in health education, case finding and case holding activities and confront failing leprosy services with their poor performance.

It is essential that the process to change involves all concerned parties from the start (governments, health workers, patients, non governmental organizations, donors, etc.). Workshops involving all stakeholders should develop guidelines that can serve as a tool for managers and decision-makers who want to review the organization of leprosy services and to devise a strategy that will make them more sustainable ( De Coster et al. 1997 ). A well-defined strategy aimed at efficient, effective and sustainable leprosy control, presented at the right time, is crucial to keeping leprosy on the agenda. Major components of this strategy are summarized in Box 2.

Continuation of early case-finding, treatment with MDT and prevention of disabilities

A high coverage of BCG-vaccination, early detection of leprosy patients, followed by treatment with MDT and the prevention of disabilities, will continue to be the cornerstone of leprosy control in the 21st century. Passive case finding will remain the most suitable method for early case finding. However, in specific highly endemic areas, where awareness, patient motivation, and diagnostic procedures are regarded as inadequate, active case finding may be pursued.

Enhancing cost-effectiveness, sustainability and equity of leprosy services through integration and combination with other disease control programmes

As a result of decreasing prevalence (and therefore workload) combined with high costs and health sector reforms, many vertical programmes that still exist (e.g. India) will be discontinued in the coming years. Instead, in order to be more efficient and cost-effective and enhance accessibility, leprosy programmes of the 21st century have to be merged with other programmes and, preferably, integrated into the general health services. Two components can be distinguished that are mutually reinforcing:

Integration at the level where services are provided: This implies that patients should be diagnosed and treated every day of the week, close to their homes, by most, if not all, health workers. Multipurpose clinics and staff should attend to the curative and preventive needs of leprosy patients. This will enhance the accessibility of leprosy services for all patients and broaden their possibilities to complete treatment. It will ensure that leprosy services continue in the decades to come ( Feenstra 1993).

Integration needs to be supported by a well-organized health system, particularly through technical support from higher levels with training, supervision, drugs supply, monitoring and policy development. The local context will determine the most feasible modality to ensure that leprosy services remain of good quality. Particularly the combination of leprosy activities with tuberculosis has shown to be a promising option. Both disease control programmes target chronic diseases and are often traditionally linked; they are based on a public health perspective with similar principles, i.e. aimed at decreasing transmission by early case finding, adequate case-holding and monitoring. In countries where a model for leprosy control is well-developed, it can be used to enhance or expand tuberculosis control. In some regions of Nepal, where the leprosy control programme is supporting tuberculosis control, the sustainability of leprosy control is enhanced because it makes leprosy activities more cost-effective. Such an approach offers good opportunities for countries such as Nigeria, where leprosy control is relatively well-established but tuberculosis control still relatively weak. Currently, combination with tuberculosis control takes place in Tanzania, Nigeria, Mozambique, Kenya, Ethiopia, and more recently in Indonesia. In other countries leprosy services are combined with dermatological services, e.g. in Vietnam, Laos, China, Brazil and Surinam. In some settings it may be possible to hand over all supportive activities to the general health services, provided, of course, that sufficient attention is given to the needs of the leprosy control programme and that the general health services are of acceptable quality.

In several countries, integration at the level of service delivery and the combination of technical support to leprosy and tuberculosis control go hand in hand. In Ethiopia leprosy services are currently integrated in the general health services at the most peripheral level, while at the same time support to this level is strengthened through the combination with tuberculosis control. The number of clinics with facilities to diagnose and treat leprosy has increased considerably and the combined training and supervision for leprosy and tuberculosis control increase the cost-effectiveness, and therefore the sustainability, of these services.

Developing tailormade leprosy control strategies

Cost-effectiveness and sustainability can also be enhanced by establishing tailormade leprosy control strategies. An approach needs to be developed that links leprosy control activities to the epidemiological situation in a country, e.g. through the use of simple Geographical Information Systems (GIS). Based on case detection rates, regions could be categorized as follows:

  • Regions with high case detection rates (> 10 per 100 000 per year);

  • Regions with moderate case detection rates (1–10 per 100 000 per year);

  • Regions with low case detection rates (< 1 per 100 000 per year).

Traditionally leprosy control has followed a blanket approach, whereby support was provided to all areas and to all health service levels, irrespective of the number of patients. This is still justified where the number of patients is high and/or more or less evenly geographically distributed. Ideally, all components of leprosy control should under these circumstances be integrated into the basic health services, and staff has to be trained in these components.

In situations with moderate case detection rates a blanket approach is rather expensive. Under such circumstances a cluster approach would be more appropriate. Services, including the training of health workers, are mainly provided in the area where the leprosy problem still exists. In Kenya, for example, most new patients come from a limited number of districts, which has consequences for the organization of leprosy services.

In low-endemicity situations an outbreak approach is needed, whereby contacts of the index case are examined. Procedures should include the verification of diagnosis and treatment of the index case and the examination of intensive contacts. The community should be informed, and the health staff in the area should be trained in diagnostic skills and case management. Routinely, the skills of health workers will mainly be limited to ‘suspecting’ leprosy.

Strengthening human resource development and management

A critical review of essentially required skills at all levels is important for working towards sustainable services. Since multipurpose workers are desirable, required leprosy-related skills need to be carefully defined and standardized, while excluding nonessential skills. Taking the recent WHO initiative on the Integrated Management of Childhood Illness (Lambrecht et al. 1999; Tulloch 1999) as an example, it may be useful to consider an equivalent approach for dermatological problems: the integrated management of skin diseases. Simple and valid algorithms on the diagnosis and management of skin lesions could help the peripheral health worker to come to meaningful decisions and actions, including those for leprosy.

A tailormade leprosy control strategy, depending on the patient load, will have substantial consequences for the specific level of expertise required. For most endemic settings, the ability to suspect leprosy and refer (S & R) to a health unit capable of diagnosing and providing treatment is the most important skill required for peripheral multipurpose health workers. The supervised provision of treatment is another task that can be delegated to the lowest level. In areas with low patient loads, management of nerve damage will have to be concentrated in health facilities with a larger catchment population, e.g. a district hospital serving 200 000–500 000. The centres for the treatment of complications of leprosy and rehabilitative surgical services will be even more concentrated. As the number of contacts between health workers and leprosy patients diminishes, fewer staff will obtain skills in case management and leprosy control. Figure 3 illustrates a hierarchical list of the required skills.

Figure 3.

Ranking of required skills in order of possibilities to delegate to peripheral health services.

To maintain minimum awareness of leprosy, leprosy must be kept in the curricula of (para) medical workers, even under low endemic circumstances. Each leprosy-endemic country should have at least one centre of excellence for complicated dermatological and surgical patient management. This need not be a special leprosy hospital, but may well be an adequately equipped general hospital.

Strengthening services at the national level

Regardless of the level of endemicity in a country, a well-functioning central unit, usually in the Ministry of Health (MoH), is necessary. The central unit should be responsible for policy formulation and technical guidance, technical training, and planning, monitoring, evaluation. MoH will need to sustain an international technical exchange of ideas and experiences. These contacts are of great importance to maintain a sense of cohesion and to facilitate innovation. Most endemic countries will want to maintain links with the national and international donor community.

MoH should be capable of formulating a long-term health policy embedding disease control policies including leprosy. This requires, however, that the national disease control units are equipped with strong skills in policy development, communication and negotiation.

Strengthening services for patients in need of medical and social rehabilitation

Worldwide, the number of ex-patients with deformities and disabilities has already surpassed the number of patients in need of MDT. Many of these people will need medical care in the form of septic or reconstructive surgery. They should have access to general surgical facilities. Due to stigma, this is still not the case in several countries.

Grouping rehabilitative interventions into ‘packages’ for specific conditions or groups of disabled persons will facilitate the decision-making and referral process, allowing individual programmes to adjust the contents of the packages according to their specific requirements. It allows for transparency in terms of who is responsible for the delivery of care. Budgets and costs could be related to the number of registered disabled patients more easily. We propose the following ‘packages’ of interventions

  • Neuritis package: early diagnosis and treatment of reactions and neuritis;

  • Self-care package consisting of health education, provision of protective materials such as footwear, bandages, sunglasses, etc.;

  • Surgical care package comprising hospitalized ulcer care, septic surgery, reconstructive surgery and orthopaedic footwear;

  • End stage or amputee package including health education and the provision of prostheses and crutches.

The level at which these packages would be provided depends on factors such as the case detection rate. Socio-economic rehabilitation (SER) of leprosy patients will remain an important issue. Severely deformed and destitute patients may continue to live in special places such as leprosaria, though admission to these places should, in general, be discouraged. Community-based rehabilitation, where these patients receive the same kind of services as other people with severe disabilities, is preferable.

Stimulating relevant research

The fact that registered prevalence is low does not mean that research is no longer needed ( ILEP 1996). Health system research in particular, formulated within the context of specific leprosy control programmes and orientated towards direct action, should be supported. In addition, three areas for further research should be prioritized:

  • Studies to determine factors influencing the transmission and to understand the impact of interventions on the epidemiology of leprosy. This will also make mathematical models to assess future trends in the epidemiology of leprosy more relevant and reliable.

  • Research to elucidate the factors that cause delay in early detection and influence health-seeking behaviour. Since stigma, health infrastructure, etc., are often context-specific, this is an area where health systems research can enhance knowledge and develop relevant interventions. Research into early diagnosis and shortened treatment schedules should be encouraged, in order to reduce defaulter rates and (opportunity) costs.

  • Research on leprosy reactions and recent nerve damage focusing on the development of tools for diagnosis and the treatment of such reactions under field conditions, e.g. standardization of the use of corticosteriods.

Conclusion

There are still substantial gaps in our knowledge of leprosy transmission and epidemiology. Only when, through further research, these gaps are closed, long-term strategies for ‘real’ elimination can be established. Currently, however, the changing circumstances, such as a decreasing registered prevalence, health sector reforms, a diminished commitment and scarcity of resources, require a fresh look at policies and strategies for leprosy control. Such a revision requires an active position by decision-makers, because attempting to carry on as usual is doomed to lead to the evaporation of leprosy control.

We have provided directions for leprosy control in the coming years, which partly build on experiences of the past and partly require the development of new approaches. Obviously, on the threshold of the new millennium, an important chapter in the history of leprosy control will be closed. However, it would be far too early to close the whole book.

Acknowledgements

The authors thank Lex Muller for his intellectual and technical support, Piet Feenstra for his useful comments and Leonie McCann for her assistance in editing an earlier draft.

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